Keywords

1 Introduction

The Fourth Industrial Revolution, also known as Industry 4.0, is changing the way businesses operate and therefore the environments in which they are forced to compete, as stated in [1]. The term “Industry 4.0” was introduced in 2011 at the Hannover Fair and immediately became the focus of attention of both the German government and other European countries [2]. Industry 4.0 is interpreted as the application of cyber-physical systems to industrial production chains, extending far beyond the limits of the Internet of Things, which is typically where many or s approaches to the phenomenon begin and end [1, 2]. The main economic potential of Industry 4.0 is its ability to accelerate corporate decision-making and adaptation processes. This applies both to processes to drive efficiency in engineering, manufacturing, services, and sales and marketing, as well as to the focus of entire business units or business model changes [2].

AM is a manufacturing technology that basically consists of the manipulation of a material on a micrometric scale, so that it melts and can be deposited gradually and very precisely, generating layer by layer a solid with the desired geometry [2,3,4]. This technology, in general, and 3D printing, in particular, allows manufacturers to obtain prototypes and proof-of-concept designs, which simplifies and streamlines the process of designing and manufacturing new products [2, 5]. The main advantage of this type of technology is that any geometry that may be needed, however complex, can be reproduced without the need for tools or complex manufacturing processes [3]. Therefore, the main characteristics that distinguish the process of manufacturing solids by addition of layers of material from any other industrial manufacturing process, and that give it enormous competitive advantages, are the following: geometric complexity and customization of the design process.

As has been explained, AM allows the design of different components with fewer restrictions than with traditional manufacturing processes and provides a much higher production capacity, which allows great improvements in production time and flexibility and cost reduction. However, although it represents a major change and advance, traditional manufacturing methods cannot be replaced due to the disadvantages of AM technologies [4]: size restrictions, production time, cost, regulation problems, limited mechanical strength, difficulty of controlling precision in manufacturing and surface quality of the parts.

In this work, the influence of different 3D printing parameters to obtain the best results from the dimensional point of view is studied. As set forth in [6], the mechanical properties of parts manufactured using 3D printing are affected by the printing parameters. This study will study the effect on dimensional stability of the following process parameters: printing temperature, filament extrusion speed and layer height.

2 Materials and Methods

2.1 Design of the Standard Part

The design has the following characteristics (see Fig. 1):

  • A square base of 20 mm side. The size of the design is designed to minimize errors that may occur in the scales of the 3D printer

  • Grooves of 3 mm wide that will serve as a stroke to have reference of the measurements.

  • Protrusions to be able to tie the piece when measuring.

Fig. 1.
figure 1

Design of the material standard.

Full size image

The design is based on a stage micrometer, which is one of the most widely used reference standards in the calibration of optical amplification measuring instruments [7]. With these measuring instruments, it is necessary to always make the same flushing and, therefore, the width of the stroke must be considered.

2.2 3D Printing Process

For the process of layering and tracing the print path of the parts, the Ultimaker Cura 4.12.1 software was used. The parts will be manufactured on an Anycubic i3 Mega 3D printer using the thermoplastic polymer polylactic acid (PLA) as a filament.

In this work, the dimensional variation obtained by varying the printing temperature, extrusion speed and layer height throughout its range will be studied. The effect of each parameter will be evaluated using five study points. To determine the printing parameters of each study point to evaluate how each parameter affects, two of the parameters are set at a reference value and the parameter to be studied is varied. The printing parameters of the different samples are shown in Table 1:

Table 1. Printing parameters.
Full size table

2.3 Measuring Process

A calibrated profile projector of horizontal axis profiles of the brand NIKON, model H14B and with serial number 10129 that allows the illumination of the samples both diascopically (by transmitted light) and episcopically (by reflected light) The measurement fields of the projector are CX = 200 mm, CZ = 100 mm y α = 360º and its resolutions are EX = EZ = 0.001 mm taken digitally and Eα = \(1^{{\prime }}\) taken analogically. For this experiment a 100X amplification will be used.

For the measurement of parts in general with profile projectors, the typical uncertainty calculated with Eq. (1) must be considered (L is expressed in meters):

$$ u \, = \, \left( {1.25 + 1.25 \cdot L} \right)\mu m $$
(1)

The distance between the midlines of the grooves that are in a vertical position will be determined. The measurements will be taken with 90º, 180º and 270º turns. Measurements will be taken at five different heights according to the measurement scheme in Fig. 2:

Fig. 2.
figure 2

Measuring strategy.

Full size image

The nominal distances of the grooves are collected in Table 2:

Table 2. Nominal distances of the grooves.
Full size table

The estimation of the uncertainty, will be accomplished considering:

  • Nominal distance between grooves (x): 13 mm.

  • Typical uncertainty (u(x)) of the measurement with the profile projector, calculated with Eq. (1): 0,018 mm.

  • For the calculation of expanded uncertainties (U(x)) a coverage factor k = 2 is used, which is the one that ensures a probability of coverage of approximately 95%.

The uncertainties of the measures shall be calculated according to Eq. (2):

$$ U\left( x \right) = k \cdot \sqrt {\frac{{s^{2} \left( x \right)}}{5} + u_{PROY}^{2} + \frac{{e^{2} }}{12}} $$
(2)

where \(s\left( x \right)\) is the standard deviation of the measurements, \(u_{PROY}\) is the uncertainty provided by the profile projector and \(e\) is the scale division of the profile projector.

3 Results

The results of the different tests are summarized in Fig. 3.

Fig. 3.
figure 3

Results of the different tests.

Full size image

4 Conclusions

From the data obtained during the present study it can be seen that:

  • The parameter that has the greatest influence seems to be the extrusion temperature.

  • There is a difference in the errors the printer makes between the X and Y axis.

  • The 3D printer needs corrections in both the X axis and the Y axis, being more necessary in the latter.

As for the study of the parameters, it seems that the printing speed and layer height do not have clear effects. However:

  • At high temperatures, lower standard deviation is obtained. In this case, the standard deviation would measure the reproducibility of the printer, that is, the ability to produce parts with the same dimensions (whatever they are, close or not to the prescribed nominals). With low temperatures, there can be variations of up to 4*s = 0.2 mm between two manufactured parts one after the other and that for a dimension of 13 mm. However, for high temperatures the above effect seems to be reduced to 4*s = 0.044 mm.

  • At high temperatures, there are fewer differences between the X and Y dimensions of the part: it goes from about 0.08 mm to only 0.02 mm. The error is divided by four.

Therefore, only temperature seems to affect. And the results are better the higher the temperature:

  • Smaller differences between the dimensions of the part in X and Y.

  • Better reproducibility (the manufactured parts have dimensions closer to each other).